diff --git a/src/frontend/numparam/xpressn.c b/src/frontend/numparam/xpressn.c
index 1424cd574..fffc12fb4 100644
--- a/src/frontend/numparam/xpressn.c
+++ b/src/frontend/numparam/xpressn.c
@@ -1531,7 +1531,7 @@ nupa_subcktcall(dico_t *dico, char *s, char * const x, char * const inst_name)
     if (i >= 0) {
         const char *optr, *jptr;
 
-        pscopy(&tstr, spice_dstring_value(&tstr), i + 7, (int) strlen(spice_dstring_value(&tstr) + i + 7));
+        pscopy(&tstr, spice_dstring_value(&tstr) + i + 7, 0, (int) strlen(spice_dstring_value(&tstr) + i + 7));
 
         /* search identifier to the left of '=' assignments */